1. Field of Invention
This invention relates to magazines for firearms. More particularly, it relates to a magazine which can store and deliver a plurality of cartridges toward the firing chamber of a firearm.
2. Background of the Invention
Magazines for guns can be separated into two categories, belt fed and spring follower.
Originally, removable box magazines were designed as single stack. Later staggered box magazines were made. Both of these magazines were straight or curved. These magazines deliver ammunition to the gun with a spring, which usually pushes the cartridges toward the gun. The spring pushes or pulls the ammunition, guided by the inner wall surface of the magazine, toward the chamber of the weapon. U.S. Pat. No. 4,139,959 to Howard, Harvey (1979) discloses a plastic magazine which utilizes a push spring and a follower to push the cartridges out of the magazine.
These magazines are limited in capacity because of spring power restrictions or friction restrictions. Magazine capacity can only be increased by lengthening the magazine, usually along the axis perpendicular to the direction which the gun fires. Even if a box magazine can solve the spring and friction problems in a high capacity magazine, the magazine would be considerably long and unwieldy.
Although box magazines are inexpensive to manufacture, considerably reliable, simple to load, simple to operate, and simple to put into or remove from the weapon, they do not possess the ability to store and deliver a high quantity of ammunition to the weapon in a reliable manner. They also do not store high quantities of ammunition in a compact, ergonomic manner.
These magazines are limited in capacity because of spring power restrictions, friction restrictions or size restrictions. Magazine capacity is usually less than a drum magazine of the same size.
Another way which ammunition can be delivered to a weapon is by feeding the ammunition to the chamber with a belt magazine. These mechanisms usually use a spring drive and axle to move a belt. The belt has spaced shelves which hold cartridges individually. U.S. Pat. No. 4,468,875 to Harrison, Retzlaff(1984) discloses a removable magazine powered by a spring motor that is directly attached to the axle to drive an endless plastic band which carries the cartridges in inserts directly to the chamber.
Drum type magazines are also a way which a considerably high quantity of ammunition can be stored and delivered to the weapon. The drum type magazine can be configured as single drum or double drum. The magazine operates by pushing ammunition about the centroidal axis of the drum with a loaded spring and a rotor arm. U.S. Pat. No. 658,700 to Sullivan (1987) discloses a double drum magazine and a single drum magazine which is capable of storing and delivering a staggered ring of cartridges with the power of a spring and rotor arm.
U.S. Pat. Nos. 4,745,842; 4,384,508; and 4,445,418 have been considered but they were found deficient for ergonomic, capacity utilization, and space utilization reasons.
The drum type magazine has some imperfections. The magazine is usually difficult to load, especially without a special tool, due to the powerful spring. The spring loaded pusher arm puts a great deal of friction between the ammunition and the inside surface of the drum magazine. This can be a problem when using ammunition which is not good (reloaded or damaged ammunition). The hub, where the spring is stored on the axis of the drum, is rather large and occupies a space which can not be used to store ammunition. As a result, it takes a significantly larger space to store ammunition in a drum magazine than in other methods. Although drum magazines carry and deliver a relatively high capacity in a portable manner, they do not optimize the size of the magazine to capacity of the magazine. They are also rather difficult and time consuming to load without tools. Reliability may also be compromised when using less than perfect ammunition.